On 3/3/2021 8:33 PM, yunqiang...@cipunited.com wrote:
On 2/23/21 3:14 AM, YunQiang Su wrote:
For MIPSr6, we may wish to use compact-branches only.
Currently, we have to use `always' option, while it is mark as
conflict with pre-R6.
cc1: error: unsupported combination: ‘mips32r2’
-mcompact-branches=always Just ignore -mcompact-branches=always for
pre-R6.
This patch also defines
__mips_compact_branches_never
__mips_compact_branches_always
__mips_compact_branches_optimal
predefined macros
gcc/ChangeLog:
* config/mips/mips.c (mips_option_override):
* config/mips/mips.h (TARGET_RTP_PIC): not trigger error for
compact-branches=always for pre-R6.
(TARGET_CB_NEVER): Likewise.
(TARGET_CB_ALWAYS): Likewise.
(struct mips_cpu_info): define macros for compact branch policy.
* doc/invoke.texi: Document "always" with pre-R6.
gcc/testsuite/ChangeLog:
* gcc.target/mips/compact-branches-1.c: add isa_rev>=6.
* gcc.target/mips/mips.exp: don't add -mipsXXr6 option for
-mcompact-branches=always. It is usable for pre-R6 now.
* gcc.target/mips/compact-branches-8.c: New test.
* gcc.target/mips/compact-branches-9.c: New test.
So I think Maciej's comment was that you simply shouldn't be using
-mcompact-branches=always at mips32r2 (or anything pre-r6) together.
I think what you're trying to do here is set up a scenario where you're
defaulting to mips32r6 and compact-branches, but not error if something
specifies -mcpu=mips32r2 or something similar, right?
Yes. If we introduce the build time option, and configure gcc with always, then
gcc will always try to
Pass -mconpact-branches=always to cc1, even we use something like:
mipsisa32r6el-linux-gnu-gcc -mips32r2 -c xx.c
It may break something.
So would it be possible to make the mips32rX (for X <6) option also turn
off compact-branches? Maciej, is that less problematical from your
standpoint? Or is this just ultimately a bad idea from start to finish?
Jeff
